Loggy, read the changelog between 3.1.4.0 and the newer versions. You'll see that 3.1.4.0 had major problems with liteon drives, ifo parsing bugs etc etc.

http://www.dvddecrypter.com/changelog.asp

3.1.5.0 was a major re-write. In theory, all of the problems that 'might' exist in 3.1.5.0 and 3.1.6.0 should be fixed in 3.1.7.0.